Tappet mechanism



May 31, 1938.

A. B. BUCKLEY TAPPET MECHANISM Filed March 23, 1957 4 Sheets-Sheet l y 1938. A. B. BUCKLEY 2,119,096

TAPPET MECHANISM 4 SheetS- -Sheet 5 Filed March 23, 1937 y 1938. A. B. BUCKLEY 2,119,096

TAPPET MECHANISM Filed March 23, 1937 4 Sheets-Sheet 4 Patented May 31, 1938 UNITED STATES PATENT OFFICE Application March 23, 1937, Serial No. 132,469 In Great Britain October 19, 1936 12 Claims. (Cl. 12390) This invention relates to tappet mechanism, particularly for the valve gear of internal combustion engines. More specifically, the invention is concerned with self-adjusting tappets of the type (hereinafter referred to as the type described) comprising a distance piece which is adapted automatically to extend with respect to the tappet body on which it is mounted to take up play, due to wear or other causes, in the tappet mechanism.

According to this invention a non-tappetactuated means is provided for controlling the operation of the distance piece. By this means the possibility of over-action of the self-adjusting distance piece due to vibrations in the tappetactuated mechanism is prevented.

The non-tappet-actuated means for controlling the distance piece may take many different forms. For example, it may comprise a releasable spring device arranged so as normally to act on the distance piece to restrain self-adjustment, or a locking and unlocking device arranged to lock together and to release the tappet body and the self-adjusting distance piece.

In tappets wherein extension of the distance piece is effected by relative rotational movement between it and the tappet body, of which two relatively rotatable parts one is incapable of being rotated, the said controlling means may 30 be a locking and unlocking device acting on the other of said relatively rotatable parts. Alternatively, when both of said relatively rotatable parts are capable of being rotated, two locking and unlocking devices may be provided acting one on each of said parts.

Constructions in accordance with this invention are shown as examples on the accompanying drawings in which:

Figure 1 is a sectional elevation of a tappet with a self-adjusting distance piece mounted thereon,

Figure 2 is a similar view of a modification of the construction of Figure 1,

Figure 3 is a sectional elevation showing the self-adjusting distance piece of Figure 1 applied to a poppet valve of an internal combustion engine and provided with one form of controlling means, and 50 Figure 4 is a section on the line 4-4 of Figure 3,

Figure 5 is a sectional elevation showing the self-adjusting distance piece of Figure 2 applied to a poppet valve of an internal combustion en- 55 gine and another form of controlling means,

Figure 6 is a section on the line 66 of Figure 5, and

Figure 7 is a section on the line of Figure 6,

Figure 8 is an elevation of a modified form of the controlling means shown in Figures 5, 6 and 7,

Figure 9 is an elevation at rightv angles to Figure 8, and

Figure 10 is a detail view of the controlling means,

Figure 11 is a sectional elevation showing the tappet and self-adjusting distance piece of Figure 2 applied to the operating gear of an overhead valve with a further form of controlling means, and

Figure 12 is a section on the line |2|2 of Figure 11,

Figure 13 is a sectional elevation showing the controlling means of Figures 11 and 12 applied to a tappet for a poppet valve,

Figure l4 is a detail view showing a modification, of the construction of Figure 13, and

Figure 15' is a sectional elevation showing a modification of the construction shown in Figure 2 with a controlling means applied thereto.

' Like reference numerals indicate like parts throughout.

In the construction shown in Figure 1, the self-adjusting distance piece comprises a body 20 which is screwed onto the upper screwthreaded end of a stem portion 2| for insertion as shown into a bore 22 in the upper end of a tappet body 23. The stem portion 2| has midway between its ends a conical shoulder which seats in the upper end of the tappet body so as to locate the stem portion in the correct position in the tappet. Alternatively, the stem portion may be integral with the tappet. The body 20 of the distance piece has in its bottom face a recess 24 in which a helical loading spring 25 of opposite hand to the screwthread on the stem portion 2| is accommodated. The spring 25 is anchored at one end to the body 20 and at'the other end to the stem portion 2| and so tends always to unscrew the body from the stem portion. Screwed on to the outside of the body is a cap 26 having within it a loose disc 21 which constitutes a yieldable head member and is pressed upwardly against the top of the cap by a conical-helical spring 28 interposed between the body 20 and the head member. An aperture 29 is provided in the top of the cap to permit a poppet valve stem 30 shown in chain lines in Figure 1, or other member to be actuated by the tappet, to engage the head member 21.

In assembling the parts of the distance piece, the cap 26 is adjusted on the body 20 so that the clearance 3! between the. latter and the head member 2'! is a predetermined amount, say the usual tappet clearance of about .004" plus the thickness of the conical-helical spring 28 when fully compressed. The cap 26 is then fixed in its adjusted position on the body 20 by a pin 32. On the drawings, the clearance 3| is shown exaggerated for clarity.

When clearance between the distance piece andthe valve stem 30 is being taken up, the body 20' and the head member 21 move as a unit under the action of the loading spring 25, but if extension of the valve stem occurs the head member 21 will be depressed by the valve stem against the action of the spring 28 while the body 20 remains stationary thus still permitting the valve to close properly. I V

In the construction shown in Figure 2, the body 20 has an integral screwthreaded stem portion 2| which is screwed into the bore 22 of the tappet. Theloading spring 25 is a torsion spring which is attached at its upper end to the lower end of the stem portion 2| and at its lower end to a plug 33 screwed into the bottom of the bore 22. The screwthreaded bore 22 is longer. than the stem portion 2| and when mounting the selfadjusting distance piece in the tappet 23, the plug 33 is first screwed to the bottom of the bore 22 and then the stem portion 2| is screwed into said bore. The latter operation winds up the loading spring 25 so that it tends to cause the stem portion to unscrew from the tappet with the result that the distance piece extends as a unit relatively to the tappet to take up tappetclearance instead of thebody 20 moving relatively to the stem portion for this purpose as in the construction shown in Figure l.

Several alternativeforms of controlling means for the purpose mentioned above which may be used with either of the self-adjusting distance pieces shown in Figures 1 and 2 will now be described.

The controlling means shown in Figures 3 and 4 is a spring device arranged to counteract the action of the loading spring 25. This spring de vice comprises a Z-shaped spring 34 formed by bending a strip of sheet metal. The lower limb of the spring which is shorter than the upper limb is fixed by a screw to a flange 35 on the tappet guide 36, and the upper limb presses downwardly on the top of the cap 26- with suificient force to prevent the latter from rotating. The free end of the said upper limb is forked to accommodate the stem 30 of the poppetvalve 38 and to permit it to be withdrawn laterally from contact with the cap 26 to release the latter which is then free to be acted upon by the loading spring 25.

It will be appreciated that the controlling means must be released to' permit the self-ad'- justing distance piece to take up clearance. To this end, an eye 39 is provided on the cross limb of the Z-shaped spring 34 for the attachment of a link to permit operation of the spring from a point outside the engine casing 40. To give access to the eye 39, an opening closed by a cover 4| is provided in the engine casing.

In practice, the controlling means will be released periodically to allow the self-adjusting dis tance piece automatically to take up any clearance due to wear after which it will be reset,

The controlling means shown in Figures 5, 6, and 7 is in the form of a locking and unlocking device arranged to lock together and release the tappet body and the self-adjusting distance piece and it comprises a U-shaped clip 42 made from flat spring steel. The cross member of the clip has in it a rectangular slot 43 and fits over flats 44 formed on opposite sides of the upper end of the tappet body 23. The side limbs of the clip are each bent inwardly so as to bear on a lower flange 45 on the cap 26, and the upper end of each side limb is reduced in width to provide a finger 46 for engagement between teeth provided around an upper flange 41 on the cap 26. The distance piece is thus locked against the action of its loading spring 25 which is not shown in Figures 5,6, and 7. The clip 42 is prevented from being accidentally dislodged from the distance piece due to vibration, when the engine is working, by the lower flange 45 on the cap 26.

To release the clip 42 to permit the distance piece to take up clearance, the side limbs of the clip have to be forced'apart to disengage the fingers 46 from the teeth on the flange 41. A clipreleasing device may be provided for this purpose, said device being preferably arranged so as to permit it to be operated from outside the engine casing.

In the modification shown in Figures 8, 9 and 10 of the foregoing construction, the cap 26 has around the top a plain flange 48 and the side limbs of the clip 42 are bent inwardly and have their. upper ends bent downwardly, see especially Figure 10. The side limbs are also cut so as to provide tongues 49 which are also bent inwardly. When the clip is sprung on to the self-adjusting distance piece, the side limbs assume a vertical position and their downwardly bent upper ends bear on top of the flange 48 as shown in Figure 9; The tongues 49 then press against opposite sides of the cap 26 which is thus held by friction against rotation due to the action of the loading spring 25. As in the construction of Figures 5, 6 and 7, thecross member of the clip has in it a rectangular slot and fits over the flats 44 formed on opposite sides of the upper end of the tappet body 23.

In constructions wherein that part of the selfadjusting distance piece which has to be locked to prevent extension of the distance piece is a rotatable part, the controlling means may be a locking and unlocking device comprising a rotatable member which is constrained to rotate with said rotatable part, a split ring encircling the rotatable member, and a locking screw acting through said ring to prevent rotation of the rotatable member. Such a construction is shown in F'gures 11 and 12. In this construction, the head, member 21 has an integral shank 50 of rectangular cross section which on opposite sides fits a rectangular opening in the top of the cap 26, see also Figure 2. Thus relative rotation between the cap 26 and the shank 50 is prevented. The shank 50 reaches through said opening and is connected by a pin joint to the lower end of a push rod 52 whereof the upper end is connected by a similar joint to the rocking lever 53 for operating the valve 54. The upper end of the tappet body 23 has on opposite sides, flats 55 which fit a correspondingly shaped hole 56 in a circular bearing member 51 mounted so as'td b able to rotate in a recess formed in the tappet guide 36. The bearing member has a peripheral groove 58 which is engaged by a locking screw 59 whereby the bearing member is retained in the recess in the tappet guide and can be held against rotation. A split wearing ring 60 is housed in the groove 58 and serves to transmit the pressure of the locking screw 59 to the bearing member 51 and also to protect the latter from being damaged by the screw. When the screw 59 is tightened the tappet body 23 is locked against rotation and rotation of the distance piece in the tappet is prevented by its connection with the push rod 52. The distance piece is thus restrained from self-adjustment.

In order to permit self-adjustment, the locking screw 59 is slackened to allow the tappet body 23 and the bearing member 51 to turn together and the engine is turned by hand or caused to run slowly under its own power. Should there be any clearance or slackness in any of the joints of the valve gear between the valve 55 and the cam 6| for operating the tappet, the tappet body will be caused to turn by the action of the loading spring 25 which is omitted from Figure 11. This results in the self-adjusting piece being extended to take up said clearance or slackness. The screw 59 is then again tightened to refix the distance piece. The head of the locking screw 59 is situated outside the engine casing 40 to permit the screw to be easily operated.

The locking and unlocking device shown in Figures 11 and 12 with slight modifications may be applied to a tappet for a poppet valve as shown in Figure 13. In this case, the cap 26 of the self-adjusting distance piece is provided with flats 62 which fit and slide within the rectangular hole 55 (see Figure 12) in the bearing member 51, and the tappet body is provided with flats 53 on opposite sides which engage corresponding flats in the tappet guide so as to prevent rotation of the tappet body while permitting it to slide freely endwise in its guide. When the looking screw 59 is tightened, extension of the selfadjusting distance piece is prevented but when said screw is slackened, the distance piece is free to be rotated by the action of the loading spring 25 (not shown in Figure 13) and carry round with it the bearing member 51. As the latter is prevented from moving in the direction of its axis of rotation by the locking screw 59, the self-adjusting distance piece is constrained to slide endwise in the bearing member to take up any tappet clearance. Instead of providing the flats 63 on the tappet body 23 for preventing rotation of the latter, a second locking and unlocking device similar to that described with reference to Figures 11 and 12 may be applied to the upper end of the tappet body 23 as shown in Figure 14.

In the construction shown in Figure 15, the stem portion 2! is screwed into a sleeve 64 and is fixed therein by a pin 65 to prevent relative movement between the body 29 and the sleeve 64. The upper end of said sleeve is screwed into the upper end of the bore 22 of the tappet body 23, and the lower end of the sleeve is reduced in diameter to provide an extension 66 which fits snugly into a correspondingly reduced plain portion of the bore in the tappet body. The plug 33 is a loose fit in said reduced portion of the bore 22 and is held against rotation therein by a removable pin 61. The stem portion 2! and the plug 33 are provided with opposed forked lugs 58, 59 respectively to which the ends of the loading spring 25 are attached. A washer 10 held in position on the top face of the tappet guide 36 overlaps the bearing member 51 of the locking and unlocking device and serves to retain said block in its recess in the tappet guide while permitting rotation of the bearing member when the screw 59 is released. Rotation of the distance piece including the sleeve 64 is prevented because the shank 50 of the head member fits, in the manner described with reference to Figure 2, the rectangular opening in the cap 26 and is connected to a push rod 52 (not shown in Figure 15).

With the form of plug 33 shown in Figure 15, the overall length of the tappet body and distance piece can be adjusted by hand to a greater extent than is possible with the construction shown in Figure 2 without unduly increasing the tension of the loading spring 25 inasmuch as when the pin 61 is removed, the plug is free to rotate on its seating in the bottom of the bore 22 while the sleeve 64 is being screwed into the tappet thus relieving the spring of excessive torsional strain. This is an advantage because it reduces the degree of accuracy required when initially machining the lengths of the various parts of the valve gear and this generally results in lower production costs. Further as the extension 66 of the sleeve 64 slides within the reduced part of the bore 22 it imparts longitudinal steadiness to the assembly independently of the fit of the screwthreaded portion of the sleeve in the upper end of said bore.

The invention is not restricted to the specific constructional details shown on the drawings. For example, the form of plug shown in Figure 15 may be used instead of the screwthreaded plug in the construction of Figure 2 and any of the devices for controlling the operation of the distance piece may be used with any of the selfadjusting distance pieces described above.

I claim:

1. The combination with a self-adjusting distance piece for tappet mechanism and comprising a body adapted when mounted on a tappet to extend with respect to the tappet to take up tappet clearance and a loading spring for effecting said extension, of a locking and unlocking device for locking together and releasing the tappet and the self-adjusting distance piece.

2. The combination with a self-adjusting distance piece for tappet mechanism and comprising a body for mounting on a tappet so as to be capable of rotating relatively to the tappet and adapted when in use to extend with respect to the tappet due to said relative rotation and a loading spring for eiiecting the relative rotation, of a locking and unlocking device for locking that one of the aforesaid relatively rotatable parts which has to be locked against rotation to prevent extension of the distance piece and for releasing said rotatable part.

3. The combination of parts claimed in claim 2, wherein the locking and unlocking device comprises a rotatable member which is constrained to rotate with said rotatable part, a split ring encircling the rotatable member, and a locking screw acting through said ring to prevent rota-' tion of the rotatable member.

4. In a tappet, the combination with a tappet body of a self-adjusting distance piece comprising a body having a stem portion, a sleeve for screwing into a screwthreaded bore in the tappet body, in which sleeve said stem portion is mounted so as to be incapable of movement relatively to the sleeve, the inner end of which bore is plain and of lesser diameter than the screwthreaded portion thereof, an extension on said sleeve fitting snugly in the inner end of the bore, a plug which is a loose fit within the inner end of the bore, a removable pin for holding the plug in position in the bore, and a torsion loading spring for effecting extension of the distance piece anchored at its ends to the aforesaid stem portion and to the plug respectively.

5. The combination with a self-adjusting distance piece for tappet mechanism adapted when mounted on a tappet body to extend with respect to said body to take up tappet clearance and a loading spring for effecting said extension, of a manually operable means for locking the distance piece against movement under the action of the loading spring.

6. The combination with a self-adjusting distance piece for tappet mechanism adapted when mounted on a tappet body to extend with respect to said body to take up tappet clearance and a loading spring for effecting said extension, of a releasable spring device arranged so as normally to act on the distance piece in opposition to the loading spring to render the latter ineffectual.

'7. The combination of a tappet body, a selfadjusting distance piece mounted on the tappet body and adapted automatically to extend in relation thereto, and locking means operated independently of the operation of the tappet for locking the distance piece against movement under the action of the loading spring.

8. The combination of a tappet body, a selfadjusting distance piece mounted on the tappet body, a torsion loading spring tending to cause the distance piece to extend with respect to the tappet body, and a locking device that is operated independently of the operation of the tappet and acts normally on the distance piece to lock the latter against the action of the loading spring.

9. The combination of a tappet body, a selfadjusting distance piece mounted on the tappet body and adapted to extend in relation thereto, which extension is effected by relative rotational movement between the tappet body and the distance piece, of which two relatively rotatable parts one is'held so as to be incapable of being rotated, means for causing rotation of the other of said relatively rotatable parts, and a locking and unlocking device acting on said other rotatable part.

10. The combination of a tappet body, a selfadjusting distance piece mounted on the tappet body and adapted to extend in relation thereto, which extension is effected by relative rotational movement between the tappet body and the distance piece, both of which relatively rotatable parts are capable of being rotated, and two locking and unlocking devices acting one on each of said relatively rotatable parts.

11. The combination of parts claimed in claim 9, wherein said locking and unlocking device comprises a bearing member which is mounted on the rotatable part of said relatively rotatable parts so as'to rotate therewith, and securing means for preventing rotation of said bearing member.

12. The combination of parts claimed in claim 10, wherein each of said locking and unlocking devices comprises a bearing member which is mounted on the rotatable part so as to rotate therewith, and securing means for preventing rotation of said bearing member.

ARTHUR BURTON BUCKLEY. 

